Surface influence on the optical properties of the isotropic phase of a chiral liquid crystal
The polarization state of light transmitted through the isotopic phase (IP) of cholesteryl nonanoate near the transition to the blue phase is experimentally examined. We have found that linearly polarized light, transmitted through the IP of cholesteryl nonanoate confined between untreated substrates, becomes slightly elliptically polarized. The dependence of the rotation of the light polarization plane on the magnetic field strength for the untreated substrates is nonlinear. For the substrates treated for a planar orientation this dependence is linear. These facts show the presence of the surface-induced optically active ordered layer on the interface between the IP and a solid substrate. The possible additional contributions to the anomalous dependence of the rotation of light polarization plane on temperature in the isotopic phase of cholesteric liquid crystal have been analyzed. The investigations of the optical rotation with two different polarimeters have been performed. The anomalous dependence of the azimuth of polarization of emergent light and linear dependence of small ellipticity of this polarization have been found. The birefringence of surface induced layer, as a source of appearance of ellipticity of polarization is posed. The results of studies of dependence of optical rotation on the magnetic field strong are agree with existence of the thin surface-induced layer.
This paper was published in SPIE Proceedings Vol. 3488